/**
 * RGB Shift Shader
 * Shifts red and blue channels from center in opposite directions
 * Ported from http://kriss.cx/tom/2009/05/rgb-shift/
 * by Tom Butterworth / http://kriss.cx/tom/
 *
 * amount: shift distance (1 is width of input)
 * angle: shift angle in radians
 */

Map<String, dynamic> DigitalGlitch = {
  "uniforms": {
    'tDiffuse': {}, //diffuse texture
    'tDisp': {}, //displacement texture for digital glitch squares
    'byp': {"value": 0}, //apply the glitch ?
    'amount': {"value": 0.08},
    'angle': {"value": 0.02},
    'seed': {"value": 0.02},
    'seed_x': {"value": 0.02}, //-1,1
    'seed_y': {"value": 0.02}, //-1,1
    'distortion_x': {"value": 0.5},
    'distortion_y': {"value": 0.6},
    'col_s': {"value": 0.05}
  },
  "vertexShader": [
    'varying vec2 vUv;',
    'void main() {',
    '	vUv = uv;',
    '	gl_Position = projectionMatrix * modelViewMatrix * vec4( position, 1.0 );',
    '}'
  ].join('\n'),
  "fragmentShader": [
    'uniform int byp;', //should we apply the glitch ?

    'uniform sampler2D tDiffuse;',
    'uniform sampler2D tDisp;',

    'uniform float amount;',
    'uniform float angle;',
    'uniform float seed;',
    'uniform float seed_x;',
    'uniform float seed_y;',
    'uniform float distortion_x;',
    'uniform float distortion_y;',
    'uniform float col_s;',

    'varying vec2 vUv;',

    'float rand(vec2 co){',
    '	return fract(sin(dot(co.xy ,vec2(12.9898,78.233))) * 43758.5453);',
    '}',

    'void main() {',
    '	if(byp<1) {',
    '		vec2 p = vUv;',
    '		float xs = floor(gl_FragCoord.x / 0.5);',
    '		float ys = floor(gl_FragCoord.y / 0.5);',
    //based on staffantans glitch shader for unity https://github.com/staffantan/unityglitch
    '		vec4 normal = texture2D (tDisp, p*seed*seed);',
    '		if(p.y<distortion_x+col_s && p.y>distortion_x-col_s*seed) {',
    '			if(seed_x>0.){',
    '				p.y = 1. - (p.y + distortion_y);',
    '			}',
    '			else {',
    '				p.y = distortion_y;',
    '			}',
    '		}',
    '		if(p.x<distortion_y+col_s && p.x>distortion_y-col_s*seed) {',
    '			if(seed_y>0.){',
    '				p.x=distortion_x;',
    '			}',
    '			else {',
    '				p.x = 1. - (p.x + distortion_x);',
    '			}',
    '		}',
    '		p.x+=normal.x*seed_x*(seed/5.);',
    '		p.y+=normal.y*seed_y*(seed/5.);',
    //base from RGB shift shader
    '		vec2 offset = amount * vec2( cos(angle), sin(angle));',
    '		vec4 cr = texture2D(tDiffuse, p + offset);',
    '		vec4 cga = texture2D(tDiffuse, p);',
    '		vec4 cb = texture2D(tDiffuse, p - offset);',
    '		gl_FragColor = vec4(cr.r, cga.g, cb.b, cga.a);',
    //add noise
    '		vec4 snow = 200.*amount*vec4(rand(vec2(xs * seed,ys * seed*50.))*0.2);',
    '		gl_FragColor = gl_FragColor+ snow;',
    '	}',
    '	else {',
    '		gl_FragColor=texture2D (tDiffuse, vUv);',
    '	}',
    '}'
  ].join('\n')
};
